In Did You Know? the National Geographic magazine team shares extra information we gathered to expand your knowledge of our featured subjects.

There are many ways to help yourself remember things. Whole systems of mnemonics, or tricks to help memory, have been developed over at least the past two millenia, from memory palaces (each item to be remembered is tagged to a location or item in an imaginary room and then is retrieved by taking a mental walk through the rooms of the palace) to acronyms to "chunking," or breaking large amounts of material into smaller, more easily remembered segments.

Some people, however, are born with an unusual capability that helps them remember things with a special flair. A condition called synesthesia links sensory experiences to objects or words or sounds. Synesthetes experience the world in a number of different ways; a common one is seeing each letter of the alphabet or each numeral as a particular color, though synesthetic combinations range widely, including feeling tastes, hearing colors, or tasting shapes, all of which make the original experience particularly vivid.

Synesthetes often have excellent memories, and seizures of the medial temporal lobe in the area of the hippocampus can induce synesthesia. If a person sees a word as mostly blue, it helps him to remember the word, as he can remember either the word itself or, more likely, the shading of the blues, which then leads him to the letters in the word itself. Alexander Luria's patient "S," who was a remarkable mnemonist with a virtually unlimited memory, experienced multiple forms of synesthesia, which gave him many mental hooks on which to hang long strings of information.